By Peter Apps, Political Risk Correspondent
WASHINGTON (Reuters) - Despite quietly dropping the phrase "war on terror", when it comes to battling worldwide militant networks the success of the United States and its allies goes well beyond the killing of Osama bin Laden.
With Britain deploying surface to air missiles, fighter jets and warships around London ahead of the Olympic Games, the threat of devastating attacks on Western nations has not gone away -- and few believe it can ever be eliminated.
Some security experts fear it may still only be a matter of time until an individual or small group use a chemical, biological or nuclear weapons -- or perhaps a cyber attack -- to inflict a death toll to dwarf that of September 11, 2001.
But in the decade since the attacks on New York and Washington killed nearly 3,000, much has changed. Quietly, many of the tactics adopted by governments have made it much harder for large, complex organizations such as Al Qaeda to operate.
On Monday, U.S. counterterrorism officials said they had frustrated a plot by al Qaeda on the Arab Peninsula to attack airliners using a redesigned version of an underwear bomb used in previous attack attempts. But they said the plot was thwarted in the early stages and no one airline was ever at risk.
"The initial asymmetric advantage Al Qaeda enjoyed has been eroded," says Nigel Inkster, a former deputy chief of Britain's Secret Intelligence Service (MI6) and now head of political risk and transnational threats at London's International Institute for Strategic Studies. "Governments, intelligence services, police and judiciaries have all learned a great deal about how terrorist organizations work and have all upped their game in dealing with the threat."
By the time Navy Seals killed bin Laden in his Pakistan compound, security experts say it appears the Al Qaeda leader had much less direct control over the militant group that he had in the pre-2001 era or even the early years that followed.
With its leadership decimated, security experts say Al Qaeda has effectively become a series of franchises and brands operating largely separately across several regions.
Some parts - particularly the largely Yemen-based Al Qaeda in the Islamic Peninsula - are still seen as an extremely serious and credible threat. But most security and intelligence experts say the overall movement is now a shadow of its former self.
A selection of letters written by bin Laden and released by the United States on Thursday showed the Al Qaeda leader himself worrying over the future of his organization, his lack of control and the difficulty of transferring money.
But it is not just Islamist militant networks that have suffered. A range of other groups, from Sri Lanka's Tamil Tigers to Colombia's FARC to Basque separatists ETA have all effectively found themselves becoming collateral damage.
The militants Western intelligence agencies fear most now, insiders say, are the "homegrown extremists" -- often radicalized online alone late at night, planning attacks sometimes guided by distant leaders and sometimes entirely independent -- and therefore almost entirely impossible to detect.
As last year's attacks in Norway by Anders Breivik, who killed 77 in an apparently solo gun and bomb attack, show, such attackers are not always Islamic and can still conduct highly destructive actions.
But security experts believe it would generally be much harder to conduct a truly coordinated spectacular such as 9/11 -- although the 2005 London underground and bus attacks showed what a small largely homegrown group could do, killing 56 including the bombers.
HIGH-TECH DATA CRUNCHING
Key to Western success against terror groups, experts say, is the much greater computing power and more sophisticated analytical tools available to intelligence services -- coupled with the much greater volume of data and clues that militants themselves often leave behind them in the information age.
"Technology has played a major role here, particularly in the arena of modern communications," says Inkster. "The "electronic exhaust" left by terrorists when they communicate has made them easier to track and sophisticated relational software has made it much easier to identify connections between people who don't want to appear connected."
On a tour of its facilities on the outskirts of the English university town of Cambridge last year, British-American technology firm i2 - which provides software to leading spy agencies and law enforcement organizations around the world - showed how that worked.
From the telephone banking records of two or three suspects - contained in spreadsheets with thousands of points of individual data - the software swiftly draws out patterns, points to shared contacts and so potential new avenues for investigation.
"With the... counterterrorism and some of the law-enforcement type dataset you have a... dataset which... might be 1 million records," Julian Midwinter, i2's vice president for sales covering Europe, the Middle East and Africa, told Reuters. "You had to work out how to distil it down to clear out the noise so you can get the vital high-value pieces of information."
Within Western states themselves, that kind of information can be used to plan surveillance or police raids. But elsewhere in the world - particularly Afghanistan, Pakistan, Somalia and Yemen - it can help provide target lists for unmanned drones and special forces raids, both of which the Obama presidency has ramped up to unprecedented levels.
In recent weeks, the Obama White House has sought to use their success against militants as a key campaigning point ahead of November's presidential election. But in reality, insiders say the current administration did little more than ramp up what was already being done in the last years of George W Bush.
"The one thing that will remain constant is the focus on special operations and drone strikes," says Douglas A. Ollivant, a former U.S. Army officer and National Security Council director for Iraq under the Bush and Obama. "There's no doubt that it would continue for increase further whoever wins in November."
Other governments, inevitably, have begun to turn such tactics on other militant groups
they face many of whom have found themselves struggling both politically and tactically in the post-911 era.
Firstly, the worldwide revulsion that followed the attacks on New York and Washington made militant attacks - particularly those with high death tolls - much less politically palatable.
In the immediate aftermath of 911, small-scale bombing campaigns conducted by Northern Irish republican militants in London and Basque ETA separatists in Spain largely petered out, partly because of tight security but also worries within militant groups over the potential political fallout.
Much tighter financial controls aimed at choking Al Qaeda funding also made it much more difficult for other groups to operate, particularly separatist groups such as the Tamil Tigers heavily dependent on funding by ethnic diasporas in other parts of the world. Outspent and heavily outgunned, they lost their three decade civil war in 2009.
With hindsight, critics say the early years after 9/11 gave authoritarian states such as China and Russia too much flexibility to crush internal dissent particularly amongst Muslim groups.
But with the phrase "war on terror" increasingly unpopular and ultimately dropped under the Obama White House, some wonder whether the taboo over terrorist tactics themselves may be beginning to lift.
Syria's opposition, for example, has received relatively little criticism of their use of insurgent tactics that include suicide bombing against a government crackdown, although it may have contributed to costing them U.S. and Arab military aid.
At the same time, there has also been a growing realization that many of the other key U.S. strategies in the "war on terror" ultimately proved counter-productive or even disastrous.
Whatever the value of the intelligence gathered by controversial techniques such as waterboarding or in much-criticized detention centers such as Guantanemo Bay or Abu Graibh, they are seen as having done long-term damage to the global reputation of the United States.
While the initial 2001 invasion of Afghanistan denied Al Qaeda the safe havens it had been using, the Afghan and Iraqi wars are widely seen to have, at least in the short-term, acted as a major recruiting tool for militant groups, as well as pushing the U.S. several trillion dollars deeper into debt.
Western states might look to be increasingly avoiding major attacks on their own soil, particularly in the last half decade, but thousands have died in bombings in Iraq, Afghanistan and Pakistan.
Finally, while al Qaeda might have been devastated overseas, it is far from clear whether the vast domestic counterterrorism bureaucracy within the United States itself - centered around the Department for Homeland Security - is effective at all.
An internal U.S. government document seen by Reuters last week made it clear the U.S. government had little or no idea if homegrown militants might be planning attacks.
Some worry another major incident could spark the same kind of reaction - or, some say, overreaction - that followed 9/11.
"There is the very real risk that the "war on terror" could come back," says former State Department spokesman PJ Crowley, now a lecturer at several universities including Penn State. "If something else big was to happen, you can never predict what the result might be."
(Reporting By Peter Apps; editing by Ralph Boulton)